Pedal assembly for electronic braking system

ABSTRACT

An electrical-mechanical brake apparatus includes a bracket and a pedal arm supported by the bracket. The bracket has a cam surface. An arm extends from the pivot arm to a follower. As the pedal arm moves toward the bracket, the follower moves along the cam surface, compressing the cam bias for simulating the feel of a purely mechanical brake system. In certain embodiments, the earn body rotates while in others the cam follower rotates.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent application Ser. No. 13/021,288 filed Feb. 4, 2011, which claims priority of U.S. Provisional Application No. 61/337,500 filed Feb. 4, 2010.

BACKGROUND OF THE INVENTION

1. Field of the Invention

An apparatus for simulating the feel of a purely mechanical brake system.

2. Description of the Prior Art

Electrical-mechanical systems for simulating the feel of a purely mechanical brake system are well known in the prior art. These systems are used, for example, with “brake-by-wire” technology. In “brake-by-wire,” the braking force is correlated with data from a sensor that tracks the position of a brake pedal instead of in a purely mechanical system where the force of the vehicle operator's foot on the brake pedal contributes to the fluid pressure in a master cylinder.

For example, U.S. Pat. No. 7,748,792 to Crombez et al. discloses a system for simulating the feel of a mechanical system when the vehicle is operated in “brake-by-wire.” It includes a bracket and a pedal arm movably supported by the bracket. Springs provide resistance to the movement of the pedal arm toward the bracket, however the resistance provided does not copy the resistance of a purely mechanical system.

Cam followers biased against rotatable cam bodies are also well known. For example, typical internal combustion engines include cam followers biased against rotatable cam bodies to open and close valves to combustion chambers. A cam follower extends to the cam body. A cam bias biases the cam follower against the cam body.

SUMMARY OF THE INVENTION

A bracket and a pedal arm is movably supported by the bracket. One of the bracket and the pedal arm presents a cam body. The other of the bracket and the pedal arm presents a cam follower. A cam bias interconnects one of the cam body and the cam follower to one of the bracket and the pedal arm to bias the cam follower and the cam body against each other. One of the cam body and the cam follower is rotatable. The cam bias interconnects the rotatable one of the cam body and the cam follower to one of the bracket and the pedal arm. The cam follower moves progressively along the cam body against resistance from said cam bias as said pedal arm moves toward said bracket for simulating the feel of a purely mechanical brake system.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages of the present invention will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is graph comparing the resistance against moving a pedal arm toward a bracket as the pedal arm approaches the bracket in a purely mechanical system with three trials of an apparatus according to the present invention;

FIG. 2 is a perspective view of an apparatus according to a first embodiment of the present invention;

FIG. 3 is a back perspective view of an apparatus according to the first embodiment of the present invention;

FIG. 4 is a side view of an apparatus according to the first embodiment of the present invention;

FIG. 5 is a position sensor according to the first embodiment of the present invention;

FIG. 6 is a perspective view of an apparatus according to a second embodiment of the present invention;

FIG. 7 is a partial sectional side view of an apparatus according to the second embodiment of the present invention;

FIG. 8 is a perspective view of an apparatus according to a third embodiment of the present invention;

FIG. 9 is a perspective view of an apparatus according to a fourth embodiment of the present invention;

FIG. 10 is a side view of an apparatus according to the fourth embodiment of the present invention;

FIG. 11 is a perspective of a pedal assembly according to a fifth embodiment of the present invention;

FIG. 12 is a side view of the pedal assembly of the fifth embodiment of the invention with a partial cut away of a cam surface;

FIG. 13 is a perspective view of a pedal assembly of a sixth alternative embodiment of the invention; and

FIG. 14 is a side view of the pedal assembly of the sixth alternative embodiment of the invention with a cut away of the cam surface.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the FIGS. 2-5, wherein like numerals indicate corresponding parts throughout the several views, an apparatus for simulating the feel of a purely mechanical brake system includes a bracket 120 including a central planar portion 122 having a lower end 124 and an upper end 126. The lower end 124 defines an aperture 128 for allowing a brake rod (not shown) to pass therethrough. The bracket 120 includes a left arm 130 and a right arm 132 spaced from each other and each extending perpendicularly upward from the upper end 126. Each of the left and right arms 130, 132 presents a flange 134 extending perpendicularly therefrom for mounting the bracket 120 to a firewall (not shown) of a vehicle.

Each of the left and right arms 130, 132 define a pivot hole 136 extending perpendicularly therethrough. Each of the pivot holes 136 is concentric to each other along a pivot axis A. A pivot rod 137 is supported by and extends through each of the pivot holes 136. A pivot tube 138 surrounds and is rotatably supported by the pivot rod. A pedal arm 140 extends between a proximal end 142 fixed to the pivot tube 138 between the left arm 130 and the right arm 132 and a distal end 144. The distal end 144 of the pedal arm 140 has a pad 146 fixed thereto.

In a first embodiment such as the apparatus shown in FIG. 2, the right arm 132 defines a sensor slot 148. The sensor slot 148 is arcuate and is concentric with the pivot axis A. The apparatus includes a position sensor 150, an example of which is a non-contacting position sensor of the type manufactured by KSR and disclosed in U.S. Pat. No. 7,221,154. The position sensor 150 has a sensor follower 152 disposed in the sensor slot 148. A pedal return rod 154 extends perpendicularly from the pedal arm 140 and parallel with the pivot axis A. A pedal return spring 156 extends from the central planar portion 122 of the bracket 120 to the pedal return rod 154 to bias the pedal arm 140 to a home position. The pedal return spring 156 has a saddle 158 disposed between the pedal return rod 154 and the pedal return spring 156 for permitting relative rotation between the pedal return rod 154 and the pedal return spring 156.

A stop arm 160 extends from the pedal arm 140. A stop bracket 162 extends from the right arm 132 and engages the stop arm 160 in home position of the pedal arm 140 to prevent movement of the pedal arm 140 past home position. A cam follower 164 is cylindrical and extends perpendicularly from the pedal arm 140 and parallel to the pivot axis A. The bracket 120 includes a cam support 166 that extends perpendicularly upward from the lower end 124 of the bracket 120 adjacent the right arm 132. A boss 168 is cylindrical and extends perpendicularly from the cam support 166 and toward the pedal arm 140. The cam support 166 includes a cam pin 170 extending outward from the boss 168.

A cam body 172 extends arcuately between a pivot end 174 hingedly fixed to the cam pin 170 and through a trough point 176 to a traveling end 178 to present a crescent-shape having an inner surface 180 being convex and facing the bracket 120 and a cam surface 182 opposite the inner surface 180 being concave. The cam surface 182 is slidably disposed against the cam follower 164. The cam body 172 has a lower anchor 184 disposed adjacent the trough point 176. The lower anchor 184 extends radially outward from the inner surface 180. A cam puller 190 is a spring that interconnects the lower end 124 of the bracket 120 and the lower anchor 184 to pull the cam surface 182 of the cam body 172 against the cam follower 164. The cam body 172 has an upper anchor 188 disposed between the trough point 176 and the traveling end 178. The upper anchor 188 extends perpendicularly from the inner surface 180 and parallel with the pivot axis A. A cam bias 186 is a spring that interconnects the upper end 126 of the bracket 120 to the upper anchor 188 to pull the cam surface 182 of the cam body 172 against the cam follower 164.

The cam follower 164 contacts the cam surface 182 of the cam body 172 adjacent the pivot end 174 in the home position of the pedal arm 140. The cam follower 164 moves progressively along the cam surface 182 from adjacent the pivot end 174 toward the trough point 176 and then toward the traveling end 178 stretching the cam bias 186 and the cam puller 190 as the pedal arm 140 rotates with the pivot tube 138 toward the bracket 120 for simulating the feel of a purely mechanical brake system. The cam follower 164 moves progressively along the cam surface 182 relieving the cam bias 186 and relieving the cam puller 190 as the pedal arm 140 rotates with the pivot tube 138 away from the bracket 120 for simulating the feel of a purely mechanical brake system.

In a second embodiment such as the one shown in FIG. 6, a pair of torsion springs 292 are disposed about a pivot tube 238 and between a left arm 230 and a right arm 232. One of the torsion springs 292 is on each side of an upper portion 242 of a pedal arm 240. Each of the torsion springs 292 engages the pedal arm 240 and a different one of the right arm 232 and the left arm 230 for opposing the movement of the pedal arm 240 about the pivot tube 238 toward the bracket 220. The pair of springs 292 bias the pedal arm 240 to a home position of the pedal arm 240.

A cam follower 264 extends perpendicularly from the pedal arm 240 parallel to the pivot axis A. A bracket 220 includes a cam support 266 extending from the lower end 224 of the bracket 220 adjacent the left arm 230. The cam support 266 presents a friction surface 296 that is arcuate. The bracket 220 includes a cam pin 270 extending from the cam support 266 parallel with the pivot axis A.

A cam body 272 extends arcuately between a pivot end 274 hingedly fixed to the cam pin 270 and through a trough point 276 and to a traveling end 278 to define a crescent-shape and a cam surface 282 being concave. The cam body 272 has a shoe 298 hingedly fixed thereto between the friction surface 296 and the cam bias 286 to provide frictional resistance to the movement of the cam body 272. The shoe 298 has a hinge end 300 being rotatably connected to the traveling end 278 of the cam body 272. The shoe 298 extends from the hinge end 300 to a friction end 302 slidably disposed against the friction surface 296. The cam body 272 has a spring retainer 304 rotatably connected to the cam body 272 between the traveling end 278 and the trough point 276 and disposed between the cam bias 286 and the shoe 298. A cam bias 286 interconnects the cam support 266 of the bracket 220 and the spring retainer 304 of the cam body 272.

In a third embodiment such as the one shown in FIG. 8, the bracket 420 has an accelerator assembly 506 mounted thereon. A pair of torsion springs 492 are disposed about the pivot tube 438 and between the left arm 430 and the right arm 432. One of the torsion springs 492 is on either side of the pedal arm 440 and each engages the pedal arm 440 and a different one of the right arm 432 and the left arm 430 for opposing the movement of the pedal arm 440 about the pivot tube 438 toward the bracket 420 and biasing the pedal arm 440 to a home position of the pedal arm 440.

A cam body 472 extends arcuately from the pedal arm 440 between a first end 508 adjacent the pedal arm 440 and along an inner surface 476 to a second end 510 to present a crescent-shape. The inner surface 476 is convex facing the distal end 444 of the pedal arm 440 and a cam surface 482 opposite the inner surface 476 is concave.

The bracket 420 includes a pair of rocker pin arms 512 each extending upward from the lower end of the bracket 420. Each of the rocker pin arms 512 defines a rocker pin hole 514 extending perpendicularly therethrough and parallel to the pivot axis A. Each of the rocker pin holes 514 is concentric to each other. The bracket 420 includes a rocker pin 516 rotatably disposed in and extending between the rocker pin holes 514.

A cam follower 464 extends from a pivot end 474 hingedly fixed to the rocker pin 516 of the bracket 420 to a traveling end 478. The traveling end 478 of the rocker arm defines a spring retainer 504 being dish-shaped. The traveling end 478 of the rocker arm also defines a pair of roller holes 518. The traveling end 478 has a roller 520 rotatably disposed in the roller holes 518 of the cam follower 464. The roller 520 of the cam body 472 is slidably disposed against the cam surface 482. A cam bias 486 is a spring interconnecting the bracket 420 and the spring retainer 504 of the cam follower 464 for pushing the cam follower 464 against the cam surface 482.

The roller 520 contacts the cam surface 482 of the cam body 472 adjacent the first end 508 in home position of the pedal arm 440. The roller 520 moves progressively along the cam surface 482 from adjacent the first end 508 toward the trough point and then toward the second end 510 compressing the cam bias 486 as the pedal arm 440 rotates with the pivot tube 438 toward the bracket 420 for simulating the feel of a purely mechanical brake system. The roller 520 moves progressively along the cam surface 482 toward the first end 508 relieving the cam bias 486 as the pedal arm 440 rotates about the pivot tube 438 toward home position for simulating the feel of a purely mechanical brake system.

A fourth embodiment such as the one shown in FIG. 9 has a pair of torsion springs 692. Each of the torsion springs 692 is disposed about the pivot tube 638 and between the left arm 630 and the right arm 632. One of the torsion springs 692 is on either side of the pedal arm 640 and each engages the pedal arm 640 and a different one of the right arm 632 and the left arm 630 for opposing the movement of the pedal arm 640 about the pivot tube 638 toward the bracket 620 and biasing the pedal arm 640 to a home position of the pedal arm 640. A position sensor 650 is fixed to the left arm 630 for detecting angular position of the pedal arm 640. A switch bracket 660 extends from the pedal arm 640 to activate a brake lamp switch. A stop bolt 722 extends through the pedal arm 640 between the cam follower 664 and the proximal end 642 of the pedal arm 640 and adjacent the cam follower 664 and is fixed to the bracket 620 for preventing the pedal arm 640 from moving past the home position of the pedal arm 640.

A cam body 672 extends from a first end 708 fixed to the lower end 624 of the bracket 620 toward the pedal arm 640 through a trough point 676 to a second end 710. The cam body 672 presents a cam surface 682 and the cam surface 682 is arcuate.

A cam follower 664 has a pivot end 674 hingedly fixed to the pedal arm 640 between the proximal end 642 and the distal end 644 and extends to a traveling end 678. The cam follower 664 includes a roller 720 rotatably mounted on the traveling end 678 of the cam follower 664 and slidably disposed against the cam surface 682.

A bias clevis 724 is hingedly mounted to the traveling end 678 of the cam follower 664. The pedal arm 640 has a bias retainer 726 hingedly mounted thereto between the pivot end 674 of the cam follower 664 and the distal end 644 of the pedal arm 640 and extending therefrom toward the bracket 620. A cam bias 686 interconnects the bias retainer 726 and the bias clevis 724. The cam bias 686 includes a bias spring 728 for pushing the cam follower 664 against the cam surface 682 and a spring collector 730 for retaining the bias spring 728.

The cam follower 664 contacts the cam surface 682 of the cam body 672 adjacent the second end 710 in home position of the pedal arm 640. The cam follower 664 moves progressively along the cam surface 682 from adjacent the second end 710 toward the trough point 676 and then toward the first end 708 compressing the bias spring 728 as the pedal arm 640 rotates with the pivot tube 638 toward the bracket 620. The cam follower 664 moves progressively along the cam surface 682 toward the first end 708 relieving the cam bias 686 as the pedal arm 640 rotates about the pivot tube 638 toward the home position for simulating the feel of a purely mechanical brake system.

A fifth alternative embodiment of a pedal assembly 810 is shown in FIGS. 10 and 11. As best shown in FIG. 10, a pedal arm 812 is pivotally mounted to a bracket 814 by a pivot pin 816. The bracket 814 has a center portion 818 extending between a pair of arms 820, 822 which support the pivot pin 816 and pedal arm 812.

A telescoping spring assembly 824 extends between the bracket 814 and a pin 826 mounted to extend outwardly from the pivot arm 812. The spring assembly includes a spring seat 828 which is pivotally mounted to the center portion 818 of the housing. A telescoping rod 832 which is biased by a main spring 834 extends from the spring seat 828 to a saddle 824. The pin 826 is pivotally received in a groove in the saddle 824. The spring 834 is captured between the seat 828 and saddle 824 to compress when the pedal arm is depressed and exerts a first biasing force to resist depression of the pedal arm. The telescoping rod 832 guides the depression as the seat pivots on pin 838.

A hysteresis assembly 840 extends between the pedal arm 812 and a cam surface 842 formed on the central portion of the bracket. The hysteresis assembly includes a hub 844, a follower or roller 846, hysteresis spring 848, and telescoping arm 850. The hub extends around the pivot pin 816 and is secured to the pedal arm by fasteners 852. The hysteresis spring 848 may have a stiffer spring constant than the main spring 836. The cam surface 842 is shaped to compress the hysteresis spring 848 increasingly as the cam roller 846 travels along the cam surface 842 during depression of the pedal arm 812. The curvature of the surface is chosen to increase or decrease the resistance to depression as the pedal is depressed to simulate the desired resultant force. The resultant force is the sum of the biasing resistance of both the main spring and hysteresis spring and provides a result such as shown in FIG. 1.

The radius of curvature of the cam surface decreases inwardly with respect to the pivot pin at an increasing rate until a slight inward hump 854 is formed in the cam surface. The radius of the curvature then increases. The cam surface begins to arc for a short distance before decreasing inwardly. The hump 854 provides a “kick down” effect.

A stop 856 for the pedal arm is formed between an arm 858 which extends along a plane which is coaxial with the pivot to support a threaded bolt 860 which is positioned to contact stop pad 826 which is mounted on a support 864 which extends from the pedal arm. The travel of the bolt may be adjusted to stop the pedal arm 812 in the proper position.

A sixth preferred embodiment of a pedal assembly 910 is shown in FIGS. 13 and 14. The sixth preferred embodiment is similar to the embodiment of FIGS. 11 and 12. A single arm 912 extends from hub 914 to a friction shoe 916 which is pivotally mounted on a free end 918 of the arm 912. A biasing arm 920 is pivotally mounted to an inner end 922 of the first arm to extend to an inner surface 924 of the friction shoe 916. An outer surface 926 of the friction shoe rides along a cam-shaped friction surface 928. Similar to the cam surface 842 of the fifth embodiment, the surface may have a texture or friction material like that of a brake shoe to generate friction. Biasing spring 930 is held in a telescoping housing 932 which is mounted at one end 934 to the housing and at another end 930 to the biasing arm 920.

When the pedal arm is depressed, the main spring 824 is compressed and the biasing spring 930 is compressed against the biasing arm 920 of the hysteresis mechanism. Compression of the biasing spring 830 forces the second arm against the end of the shoe 916 to push the shoe 916 into contact with the cam surface 928 of the housing. As the shoe travels along the cam surface, the force increases against the shoe until it travels over a kickdown hump thereby simulating a kickdown effect.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings and may be practiced otherwise than as specifically described while within the scope of the appended claims. These antecedent recitations should be interpreted to cover any combination in which the inventive novelty exercises its utility. In addition, the reference numerals in the claims are merely for convenience and are not to be read in any way as limiting. 

1. A pedal assembly for a pedal arm of a vehicle comprising: a bracket for pivotally supporting the pedal arm about a pivot axis, the bracket having a cam surface positioned radially outward from the pivot axis; an arm extending from the pedal arm to the cam surface; a follower mounted to an end of the arm; a biasing spring forcing the follower member against the cam surface such that hysteresis is generated when the pedal arm is depressed.
 2. The pedal assembly of claim 1, wherein the pedal assembly further comprises a main spring extending between the pedal arm and the bracket.
 3. The pedal assembly of claim 1, further comprising a hub mounted to the pedal arm about the pivot axis and wherein the arm extends from the hub.
 4. The pedal assembly of claim 3, wherein the follower is a roller.
 5. The pedal assembly of claim 4, further comprising a hysteresis spring extending between the roller and the hub.
 6. The pedal assembly of claim 5, wherein the arm is a telescoping arm.
 7. The pedal assembly of claim 1, wherein the follower is a shoe.
 8. The pedal assembly of claim 7, further comprising a biasing arm extending between one end of the arm and the shoe.
 9. The pedal assembly of claim 8, wherein the biasing spring extends between the bracket and the biasing arm. 